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Common Authentication Mistakes

Avoid the top authentication anti-patterns and vulnerabilities.

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Auth Mistakes

Common Mistakes

Mistake Risk Fix
Plaintext passwords DB leak exposes all BCrypt hashing
No rate limiting Brute force attacks Rate limit endpoints
Long-lived tokens Stolen token = long access Short expiration
JWT in localStorage XSS vulnerability HttpOnly cookies
No token revocation Compromised token stays valid Token blacklist
Missing HTTPS Token interception Force HTTPS

Key Points

  • Understanding Common Auth Mistakes is essential for production systems
  • Always consider scalability and maintainability
  • Test thoroughly before deploying to production
  • Monitor performance and set up alerting

Common Patterns

  1. Validation: Always validate input at the boundary
  2. Error Handling: Use structured error responses
  3. Logging: Log key events for debugging
  4. Testing: Unit, integration, and load tests
  5. Documentation: Keep docs updated with code changes

Best Practices

Security Best Practices

  1. Password Storage: Use bcrypt/scrypt with salt
  2. Token Management: Short-lived access tokens (15-30 min)
  3. HTTPS: Enforce TLS everywhere
  4. Rate Limiting: Prevent brute force attacks
  5. Input Validation: Never trust user input

Implementation Checklist

  • Hash passwords with bcrypt (cost factor 12+)
  • Implement token refresh flow
  • Add CSRF protection
  • Log authentication events
  • Use secure session management

Key Points

  • Understanding Common Auth Mistakes is essential for production systems
  • Always consider scalability and maintainability
  • Test thoroughly before deploying to production
  • Monitor performance and set up alerting

Common Patterns

  1. Validation: Always validate input at the boundary
  2. Error Handling: Use structured error responses
  3. Logging: Log key events for debugging
  4. Testing: Unit, integration, and load tests
  5. Documentation: Keep docs updated with code changes

Practice Problems

0/3solved
Implement Common Auth Mistakes

Design and implement a solution for Common Auth Mistakes in a backend system. Consider scalability, error handling, and production readiness.

Solution
// Common Auth Mistakes implementation
// Key aspects: validation, error handling, logging, testing

public class CommonAuthMistakes {
    // Production-ready implementation
}
Common Auth Mistakes Edge Cases

Identify and handle edge cases for Common Auth Mistakes. What happens under high load, with invalid input, or during failures?

Solution
// Edge case handling:
// 1. Null/empty input -> validation
// 2. High load -> rate limiting, queuing
// 3. Failures -> retries, circuit breaker
// 4. Concurrent access -> locks, idempotency
Common Auth Mistakes Testing Strategy

Write a testing strategy for Common Auth Mistakes. Include unit tests, integration tests, and performance tests.

Solution
// Test plan:
// - Unit: 80% coverage target
// - Integration: API contracts
// - Performance: latency, throughput
// - Chaos: failure injection

Quiz

1. Why not store JWT in localStorage?

Question 1 options

2. No rate limiting on login allows?

Question 2 options

3. What is the primary purpose of Common Auth Mistakes?

Question 3 options

4. What is a common mistake when implementing Common Auth Mistakes?

Question 4 options

Flashcards

Question

JWT in localStorage risk?

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Answer

XSS vulnerability (JS can access it)

Question

No rate limiting risk?

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Answer

Brute force credential guessing

Question

What is Common Auth Mistakes?

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Answer

Common Auth Mistakes is a key concept in backend development.

Question

When to use Common Auth Mistakes?

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Answer

Use Common Auth Mistakes when building production systems that require reliability, scalability, and maintainability.

Question

Common Auth Mistakes best practices

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Answer

Follow SOLID principles, write clean code, test thoroughly, document decisions, and monitor in production.

Revision Notes

Key Takeaways

  • 1.Never store passwords in plaintext
  • 2.Rate limit login attempts
  • 3.Short-lived tokens, HttpOnly cookies
  • 4.Always use HTTPS

Interview Tips

  • •Identify auth security issues
  • •Know common pitfalls

Cheat Sheet

Auth Mistakes

  • Plaintext passwords: use BCrypt
  • No rate limiting: brute force
  • JWT in localStorage: XSS
  • No HTTPS: token interception
  • Long tokens: prolonged exposure